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Comparison
Verdict in brief
The Duo-tec Compact 30GA and Luna Duo-tec 40GA are the two smaller Baxi Luna Duo-tec combis, both wall-hung condensing units printing 95% AFUE with 5.5:1 central-heating and 7:1 DHW-mode turndown. The 40GA fires 32 MBH higher (125 MBH versus 93 MBH input), delivers more hot water (3.9 GPM versus 2.5 GPM at a 70°F rise), and sits in the taller, heavier 102 lb cabinet — while the Compact's 79 lb, 27.5 in high chassis is the space-saving entry.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Baxi Duo-tec Compact 30GA | Baxi Luna Duo-tec 40GA |
|---|---|---|
| Input (as printed) | 93 MBH | 125 MBH |
| dhw-input-max | — | — |
| Efficiency (as printed) | 95% AFUE | 95% AFUE |
| Domestic hot water flow rate (as printed) | 2.5 GPM @ 70°F temperature rise | 3.9 GPM @ 70°F temperature rise |
| Turndown, central-heating mode (as printed) | 5.5:1 | 5.5:1 |
| Turndown, DHW mode (as printed) | 7:1 | 7:1 |
| Burner / heat exchanger (as printed) | Stainless steel ANSI 316L pre-mixed burner and heat exchanger | Stainless steel ANSI 316L pre-mixed burner and heat exchanger |
| Circulator pump (as printed) | Two-speed modulating pump with built-in air vent | Two-speed modulating pump with built-in air vent |
| Dimensions (as printed, W x D x H) | 15.75"(w) x 11.75"(d) x 27.5"(h) | 17.72"(w) x 13.59"(d) x 30"(h) |
| Weight (as printed) | 79 lb | 102 lb |
| Vent material (as printed) | Coaxial or two-pipe polypropylene | Coaxial or two-pipe polypropylene |
| Gas type (as printed) | Natural Gas / Propane | Natural Gas / Propane |
Both combis sit in the 'Combi Boilers' group of baxiboilers.com's live boiler category and share the platform's printed feature set: 95% AFUE, ENERGY STAR certification, THINK combustion management with GAC, stainless steel ANSI 316L pre-mixed burner and heat exchanger, 5.5:1 central-heating and 7:1 DHW-mode turndown, and coaxial or two-pipe polypropylene venting with Natural Gas / Propane gas type.
The difference is the firing package: the Duo-tec Compact 30GA prints 93 MBH input with 2.5 GPM domestic hot water flow at a 70°F rise, while the Luna Duo-tec 40GA prints 125 MBH input and 3.9 GPM at the same rise. Both carry the enhanced stainless steel secondary heat exchanger that delivers DHW and the pre-heating function printed on the combi pages.
Packaging decides between them as much as load: the Compact stands 27.5 in high, is 11.75 in deep, and weighs 79 lb with an international expansion tank, pump exerciser and closet-install approval printed on its page; the 40GA stands 30 in high, is 13.59 in deep, weighs 102 lb and also prints closet-install approval. Both are current products — neither page carries a discontinued banner.
The Baxi Duo-tec Compact 30GA is a 93 MBH wall-hung condensing combi on baxiboilers.com — 95% AFUE as printed, 7:1 DHW-mode turndown and 2.5 GPM @ 70°F temperature rise — modelled from its official current product page.
The Baxi Luna Duo-tec 40GA is a 125 MBH wall-hung condensing combi on baxiboilers.com — 95% AFUE as printed, 7:1 DHW-mode turndown and 3.9 GPM @ 70°F temperature rise — modelled from its official current product page.
The Luna Duo-tec 40GA: its page prints 3.9 GPM of domestic hot water at a 70°F temperature rise against 2.5 GPM on the Duo-tec Compact 30GA page.
Yes — 27.5 in high, 11.75 in deep and 79 lb against the 40GA's 30 in, 13.59 in and 102 lb, per the printed page bullets.
Yes. As of September 9, 2026 both pages are live in the Combi Boilers category with no discontinued banner, so Boilers.ca records both as current.
A consultation includes a heat-loss review so the size is right the first time.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.